Dickinson



Sept. 18, 1962 R. s. DICKINSON ET AL 3,054,260

HYDRAULIC SYSTEM FOR CONTROLLING THE POSITION OF A HYDRAULICALLY DISPLACEABLE MEMBER Filed Feb. 3, 1960 4 Sheets-Sheet 2 I33 & |G

BMMLD S/DNE) D/ mmoN MERV )N fifiR RH/H Inventors M, B MQWQLMW Attorney;

Sept. 18, 1962 R. s. DICKINSON AL 3,054,260

HYD LIC SYSTEM FOR CONTROLL E POSITION A HYDRAULICALLY DISPLACEAB MEMBER 4 Sheets-Sheet 3 Filed Feb. 5, 1960 I I l a? 705 "IZYWKWV lnenlor; 501v A-LD SID/HE b ckl/usom mEAVY/v A/iAT/LAM --FIG. 5.- W'BMW, Attorne P' 1962 R. s. DICK] ON ETAL 3,054,260

HYDRAULIC sI TEM FOR 0 ROLLING THE POSITION OF A HYDRAULICALLY DISPLACEABLE MEMBER Filed Feb. 3, 1960 4 Sheets-Sheet 4 -FIG. 7.

IX/ln MLD sin v5 DmKwso Inventors menu BALTI-R-In g f h W Attorneys Unite tes Patet 3,054,260 HYDRAULIC YS'IEM FOR CONTROLLING THE POSITION OF A HYDRAULICALLY DISPLACEA- BLE MEMBER Ronald Sidney Dickinson and Mervyn Bartram, York, England, assignors to Armstrong Patents Co. Limited, Beverley, England, a company of Great Britain Filed Feb. 3, 1960, Ser. No. 6,532 Claims priority, application Great Britain Feb. 12, 1959 12 Claims. (Cl. 60-51) This invention concerns hydraulic pumps, and relates particularly to hydraulic pumps for supplying a source of hydraulic medium under pressure incorporated in a hydraulic system wherein said medium is emeployed, under the control of position sensing means, to operate a hydraulically displaceable member such as a ram. Typical such systems are vehicle and other suspension systems wherein the attitude of a suspension spring relative to a load which it supports is modified in dependence upon the value of the supported load in order to maintain that load in a desired mean position.

In its broadest aspect, the present invention provides a hydraulic pump comprising a pump body formed with a reservoir for a hydraulic medium, a semi-rotary spindle journalled in said body and adapted for angular reciprocation from externally thereof, at least one pumping element arranged in a cylinder provided therefor in said pump body, one end of said cylinder communicating with said reservoir, means carried by said spindle for reciprocating said pumping element in said cylinder to transfer hydraulic medium from said reservoir through a pump inlet valve in said pumping element to the end of said cylinder remote from said reservoir, an outlet connection provided on said pump body, said outlet connection being adapted for connection to a pressure accumulator, a pump delivery valve arranged to permit the flow of hydraulic medium from said last-mentioned cylinder end to said outlet connection, and an inlet connection provided on said pump body and adapted for connection to a hydraulic operating member such as a hydraulic ram communicating with said pressure accumulator, said inlet connection opening into a passage provided in said pump body and leading to said reservoir, whereby when said operating member is restored from an operated position towards a rest position, hydraulic medium is enabled to exhaust back to said reservoir.

The pumping element may either be a piston connected to a crank carried by the semi-rotary spindle, or a plunger resiliently urged to bear against a cam on said spindle, and preferably at least two such pumping elements are provided, arranged symmetrically relative to the spindle to enable the pump to be double-acting.

In order to avoid a hydraulic lock between the pump and the pressure accumulator when connected thereto, the pump may further comprise an adjustable overload valve disposed in a passage formed in the pump body between the outlet connection thereof and said reservoir, and such overload valve may, if desired, constitute a damping valve for imparting a shock-absorbing action to the, pump.

Where the pump is intended for incorporation in a hydraulic system having a hydraulic operating member designed, after displacement thereof, to restore to' a mean or rest position, the pump body may further include a hydraulic medium pressure relief valve arranged in the passage between the inlet connection and the reservoir, said relief valve having a valve member adapted for unseating by means of a cam fixedly secured in a desired angular relationship on the semi-rotary spindle and the spindle may be connected to said operating member in such a manner that when said operating member is displaced in a given direction away from its mean or rest position, the cam unseats the relief valve member, and hydraulic medium is permitted to exhaust from said operating member back to the reservoir until the mean or rest position is regained. In this way, the semi-rotary spindle and the relief valve operating cam act as a posi- Lion-sensing means for the hydraulic operating member.

Although, in a hydraulic system incorporating the pump proposed by the invention, the pressure accumulator and the hydraulic operating member may be connected together independently of the pump by means of a pipe extending between the two, a particularly compact arrangement results if the pump body is further formed with a passage between the inlet and outlet connections thereof to enable said accumulator and operating memher to communicate with one another through said body, and said passage is provided with a non-return valve having a valve member adapted for unseating by means of a further cam so positioned on the said spindle as to open said valve only when the aforementioned relief valve is closed, and vice-versa.

In a modification of the invention, instead of or in addition to providing one integral reservoir in the pump body, the pump body may have means for communicating with an independent reservoir arranged externally of said body.

The invention will be described further, by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a hydraulic system incorporating a hydraulic pump embodying the invention,

FIG. 1a is a partial schematic diagram of the hydraulic system disclosed in FIG. 1 showing a modification thereof,

FIG. 2 is a vertical sectional elevation, taken on the line II--II of FIG. 3, of one construction of hydraulic pump according to the invention,

FIG. 3 is a transverse vertical section taken on the line III-III of FIG. 2,

FIG. 4 is a sectional elevation similar to that of FIG. 2 and taken on the line IV-IV of FIG. 5, of a modified construction of pump,

FIG. 5 is a transverse sectional elevation taken on the line VV of FIG. 4,

FIG. 6 is a sectional detail taken on the line VIVI of FIG. 5,

FIG. 7 is a sectional elevation corresponding to that of FIGS. 2 and 4, and taken on the line VII-VII of 'FIG. 8, through another embodiment of hydraulic pump constructed according to the invention,

FIG. 8 is a transverse sectional elevation taken on the line VIIIVIII of FIG. 7, and

FIG. 9 is a sectional detail taken on the line IXIX of FIG. 8.

Throughout the several figures of the drawings, like reference numerals are employed wherever appropriate to denote like parts.

FIG. 1 of the drawings shows a typical hydraulic system to which a hydraulic pump as proposed 'by the invention may be applied, and illustrates an arrangement wherein a pump body 10 is formed with a pair of cylinders 12 in parallel, side-by-side relationship, each of the cylinders 12 receiving a pumping element 14. The upper end of each cylinder 12 communicates with a reservoir 16 which may, as shown in FIG. 1, be arranged independently of the body 10, or may be formed therein as shown at 15 in FIGS. 2 and 3, and the pumping elements 14 are arranged for reciprocation by means 18 carried on a semi-rotary shaft 20' adapted for angular reciprocation from externally of the body 10 in any conven- Thus, after the ram has once been extended by the supply of hydraulic medium thereto by the pressure accumulator, if the vehicle loading changes in such a way as to cause spindle to bring the cams 48 and 50 into a position wherein the valve 54 is opened and the valve 52 is closed, then hydraulic medium is allowed to flow from the ram, through the bore 96, past the valve member 58 and fluted plunger 1%, and back into the reservoir 15.

FIGS. 4 to 6 show a modification of the construction of FIGS. 2 and 3, in which the overload valve 76 to 82 of FIGS. 2 and 3 is arranged, not between the outlet connection 74 and reservoir 15, but between the cylinders 12 themselves in such a manner as simultaneously to act as a shock absorber means. For this purpose, below the cylinders 12, the pump body 10 is bored at 102 to provide a passage which communicates with each cylinder through an opening 104, and the outer end of the passage 102 is closed by a plug 106 threadedly engaged in body 10 and axially bored and counterbored to provide a guideway for the spigot 108 of a first damper valve member 110, and a valve seat 112 for a second damper valve member 114. The valve member 114 is made of hollow construction to permit fluid flow therethrough to provide a valve seat 116 for the valve member 110, and to receive the other end of spigot 108, and the said valve members are urged on to their respective seats by means of springs 118 and 120. Thus there is provided a composite damper valve assembly of coaxial construction, the setting of the springs 118 and 120 determining the maximum pressures which may be exerted by the pistons in their cylinders 12 before one or the other of the damper valve members 110 and 114 is caused to lift from its seat. Should the aforementioned maximum pressure be exceeded in either cylinder 12, then the appropriate valve member lifts to allow the movement of hydraulic medium from the cylinder 12 concerned to the other cylinder 12, rather than delivering said hydraulic medium to the outlet connection 74 against the pressure of the hydraulic medium already stored in the pressure accumulator. By suitably adjusting the clearance between each valve member and its seat, the movement of hydraulic medium between the cylinders 12 can be restricted to further provide a shock absorbing action to the piston 60 and hence to the spindle 20 should the pistons be abruptly displaced in cylinders 12 as the vehicle passes over a bump.

It will be noted that the plug 106 is externally grooved at 122 to register with the opening 104 leading from the left-hand cylinder 12 (as viewed in FIG. 4), and that generally radial ports 124 lead from the groove 122 to the plug counterbore to enable the left-hand cylinder 12 to communicate with the bore 102 via the valve member 110 and its seat 116. Again, instead of the delivery conduits of FIGS. 2 and 3, the construction of FIGS. 4 to 6 provides delivery conduits 71 leading from the bore 102 to the outlet connection 74, the delivery valves 72 being arranged in the conduits 71. Since the damper valve assembly is also the overload valve in this construction, the passage also conveniently enters directly into the bore 86 housing the accumulator control valve. The remaining features of construction and operation of this embodiment of the invention are otherwise identical with those of FIGS. 2 and 3.

A further embodiment of the invention is shown in FIGS. 7 to 9, in which the pistons 60 of the preceding construction are replaced by pump plunger assemblies. Each cylinder 12 has threadedly engaged therein a cylindrical liner 126 which displaceably receives a pump plunger 128 having its upper end extending from the liner 126 towards the spindle 20. The spindle 20 has a cam 130 fixedly secured thereon, and the plungers are resiliently urged against said cam by means of springs 132, so that when the spindle is angularly reciprocated, the plungers 128 are reciprocated within their liners. Each plunger is formed with passage means 134 by which it communicates with the reservoir 15, and at its inner end, within the liner 126, is provided with a shoulder to recieve a valve seat 136 against which a ball valve member 138 is urged by means of springs 140. Beyond the valve seat 136, the passage means 134 is enlarged to form a chamber 142, and thus, on upward i.e. induction strokes of the plungers 128, hydraulic medium is drawn from the reservoir 15, past the ball valve member 138 and into the chamber 142. At the ends of the liners 126 remote from those at which the plungers are introduced, there is threadedly engaged in each said liner, a member 144 which is bored to communicate with chamber 142 and counterbored to present a shoulder receiving a valve 146 whereon resiliently abuts an output ball valve member 148. The ball valve member 148 is housed in an end cap 150 closing the member 144 except for apertures 152 through which hydraulic medium is delivered, on downward strokes of the associated plunger, from the chamber 142 to the cylinder 12. In all other respects, the construction and operation of this embodiment of the invention is identical to that of the embodiment of FIGS. 2 and 3.

We claim:

1. A hydraulic system comprising a hydraulically displaceable member and a hydraulic pump constituting a source of hydraulic medium under pressure for operating said member, said hydraulic pump comprising an at least partly hollow body member, the hollow interior of said body member constituting a reservoir for hydraulic medium, a spindle journalled in and rockable relative to said body member and extending into the hollow interior thereof, said spindle being adapted for angular reciprocation from externally of said body member, at least one hydraulic cylinder in said body member, one end of said hydraulic cylinder communicating with said hollow interior, a pumping element in said cylinder, means arranged between said pumping element and said spindle for eifecting reciprocation of said pumping element in said cylinder responsive to turning movements of said spindle, a pump inlet valve in said pumping element for passing hydraulic medium through said pumping element from said reservoir and into the end of said cylinder remote from said reservoir during movement of said pumping element in one direction in said cylinder, hydraulic medium outlet means in said body member, means including a pump delivery valve connecting said outlet means with said remote end of said cylinder for enabling hydraulic medium to pass from said remote end of said cylinder to said outlet means during movement of said pumping element in the other direction in said cylinder, hydraulic medium inlet means in said body member, said hydraulically displaceable member being connected to said inlet means and said body member being formed with a first passage extending between said inlet means and said reservoir, a first valve means in said first passage to control the flow of hydraulic medium from said inlet means into said reservoir, said body member being formed with a second passage interconnecting said inlet means and said outlet means, a second valve means in said second passage to control the flow of hydraulic medium from said outlet means to said inlet means, and cam means rotatably displaceable by said spindle and cooperating with said first and second valve means, responsive to the angular position of said spindle relative to said body member, to open said first valve means and close said second valve means when said spindle turns in one direction relative to said body member, and to close said first valve means and open said second valve means when said spindle turns in the opposite direction.

2. A hydraulic pump as set forth in claim 1, wherein said cam means are fixed on said spindle and said valve means are plunger-operated, said cam means being arranged to act on the operating plungers of said valve means.

3. A hydraulic pump as set forth in claim 1, wherein the part of said second passage between said outlet means and said second valve means is continued to communicate with said reservoir, and said passage continuation has a non-return overload valve therein to permit the flow of hydraulic medium from said outlet means to said reservoir whenever the pressure of hydraulic medium in said outlet means exceeds a predetermined value.

4. A hydraulic pump as set forth in claim 1, wherein said pumping element is a pump piston, and said pump further comprises a crank carried by said spindle and a connecting rod connecting said piston to said crank.

5. A hydraulic pump as set forth in claim 1, wherein said pumping element is a pump plunger, and said pump further comprises second cam means fixed on said spindle, and resilient means in said cylinder for urging said pump plunger against said second cam means.

6. A hydraulic system comprising a hydraulically displaceable member and a hydraulic pump constituting a source of hydraulic medium under pressure for operating said member, said hydraulic pump comprising an at least partly hollow body member, the hollow interior of said body member constituting a reservoir for hydraulic medium, a spindle journalled in and rockable relative to said body member and extending into the hollow interior thereof, said spindle being adapted for angular reciprocation from externally of said body member, said body member being formed with a pair of hydraulic cylinders, a hollow piston closed at its head end and slidably received in each of said hydraulic cylinders, means connecting said pistons with said spindle for reciprocation of said pistons in said cylinders responsive to turning movements of said spindle, a non-return valve in the head end of each piston for passing hydraulic medium from said reservoir through said piston and into the hydraulic cylinder thereof as said piston is retracted in said cylinder, hydraulic medium outlet means in said body member, means including a pump delivery valve connecting the head end of each cylinder with said outlet means for enabling hydraulic medium to pass from said head end of each cylinder to said outlet means when the piston in said cylinder is displaced towards said head end thereof, hydraulic medium inlet means in said body member, said hydraulically displaceable member being connected to said inlet means and said body member being formed with a first passage extending between said inlet means and said reservoir, a first plunger-operated valve in said first passage to control the flow of hydraulic medium from said inlet means into said reservoir, said body member being formed with a second passage interconnecting said inlet means and said outlet means, a second plunger-operated valve in said second passage to control the flow of hydraulic medium from said outlet means to said inlet means, and a pair of cams carried by said spindle and arranged to bear on the operating plungers of said valves, to open said first valve and close said second valve when said spindle turns in one direction relative to said body member, and to close said first valve and open said second valve when said spindle turns in the opposite direction.

7. A hydraulic pump as set forth in claim 6, wherein the part of said second passage between said outlet means and said second plunger-operated valve is continued to communicate with said reservoir, and said passage continuation has a non-return overload valve therein to permit the flow of hydraulic medium from said outlet means to said reservoir whenever the pressure of hydraulic medium in said outlet means exceeds a predetermined value.

8. A hydraulic pump as set forth in claim 6, wherein said body member is formed with a chamber interconnecting the head ends of said hydraulic cylinders, and wherein said chamber is provided with overload valve means comprising a first valve seat in said chamber intermediate said two cylinder head ends, a first overload valve member resiliently urged on to said first seat, said valve member being formed with an axial passage therethrough, a second valve seat surrounding said axial passage at one end face of said first valve member, and a second overload valve member resiliently urged against said second valve seat, the pump delivery valves being arranged to deliver hydraulic medium from said chamber to said outlet means against the reaction offered by said overload valve means, said delivery valves communicating with said chamber one on each side of said overload valve means.

9. A hydraulic system comprising a hydraulically displaceable member and a hydraulic pump constituting a source of hydraulic medium under pressure for operating said member, said hydraulic pump comprising an at least partly hollow body member, the hollow interior of said body member constituting a reservoir for hydraulic medium, a spindle journalled in and rockable relative to said body member and extending into the hollow interior thereof, said spindle being adapted for angular reciprocation from externally of said body member, said body member being formed with a pair of hydraulic cylinders, a reciprocable plunger slidably received in each hydraulic cylinder, each plunger being axially bored and counterbored, said axial bore communicating with said reservoir, a valve seat in said plunger at the junction of the bore and counterbore therein, an inlet valve member resiliently urged against said valve seat for passing hydraulic medium from said reservoir through said plunger and into the hydraulic cylinder thereof as said plunger moves in one direction in said cylinder, first cam means carried by said spindle, spring means in each cylinder urging the plunger therein against said cam means, whereby said cam means effect reciprocation of said plunger responsive to turning movement of said spindle, hydraulic medium outlet means in said body member, means including a pump delivery valve connecting the end of each cylinder remote from said spindle to said outlet means to enable hydraulic medium to pass from said remote ends of said cylinders to said outlet means as each plunger is moved in the other direction in its cylinder, hydraulic medium inlet means in said body member, said hydraulically displaceable member being connected to said inlet means and said body member being formed with a first passage extending between said inlet means and said reservoir, a first plunger-operated valve in said first passage to control the flow of hydraulic medium from said inlet means into said reservoir, said body member being formed with a second passage interconnecting said inlet means and said outlet means, a second plunger-operated valve in said second passage to control the flow of hydraulic medium from said outlet means to said inlet means, and second cam means carried by said spindle and bearing on the operating plungers of said valves to open said first valve and close said second valve when said spindle turns in one direction relative to said body member, and to close said first valve and open said second valve when said spindle turns in the opposite direction.

10. In a hydraulic system for controlling the position of a hydraulically displaceable member having a reciprocable pump device, a reservoir for hydraulic medium connected to the low pressure side of said pump device and means for actuating said pump device, the improvement which comprises control means for controlling the delivery of hydraulic medium from said pump device comprising means forming a first passage between the high pressure side of said pump device and said reservoir, a first valve at the pump side of said first passage, 8. second valve at the reservoir side of said passage, cam means for controlling said valves in accordance with the position of said displaceable member so that when said displaceable member is at a rest position both said first and said second valves are closed and when said displaceable member is at a position other than rest one of said valves remain closed and the other of said valves is opened, respectively, means forming a second hydraulic passage connected to said first hydraulic passage intermediate said first and said second Valve means and to said hydraulically displaceable member, means forming a third passage forming a parallel hydraulic circuit with said first passage and a non-return overload valve in said third passage to permit the flow of hydraulic medium from the high pressure side of said pump to reservoir whenever the pressure at the high pressure side of said pump exceeds a predetermined value.

11. In a hydraulic system for controlling the position of a hydraulically displaceable member having a double acting pump device, a reservoir for hydraulic medium connected to the low pressure side of said pump, said pump including a pair of oppositely reciprocated pumping elements and means for actuating said pumping elements, the improvement which comprises control means for controlling the delivery of hydraulic medium from said pump device comprising means forming a first passage between the high pressure side of said pump device and said reservoir, a first valve at the pump side of said first passage, a second valve at the reservoir side of said passage, cam means for controlling said valves in accordance with the position of said displaceable member so that when said displaceable member is in a rest position both said first valve and said second valve are closed and when said hydraulic displaceable member is in a position other than a rest position, one of said valves is opened and the other of said valves is closed, respectively, means forming a second hydraulic passage connected to said first hydraulic passage intermediate said first and said second valve means and to said hydraulically displaceable member, and overload valve means between each pumping element of said pump device for bypassing said first passage means so that said pump device is inefiective when the pressure at the high pressure side of said pump device exceeds a predetermined value.

12. In a hydraulic system for maintaining a substantially mean position of a hydraulically displaceable memher and including a reciprocable pump device housed within a body member, a reservoir for hydraulic medium communicating with the low pressure side of said pump device, means including a rockable spindle journalled in said body member for actuating said pump device and a connection between said spindle and said hydraulically displaceable member, the improvement which comprises control means for controlling delivery of hydraulic medium from said pump device comprising means in said body member forming a first passage between the high pressure side of said pump device and said reservoir, a first valve at the pump side of said first passage, a second valve at the reservoir side of said passage, cam means operable by said spindle for controlling said valves in accordance with the position of said displaceable member so that when said displaceable member is displaced in one direction relative to said mean position said first valve is opened and said second valve is closed, when said displaceable member is displaced in the opposite direction said first valve is closed and said second valve is opened, and when said displaceable member occupies said mean position both said valves are closed, means forming a second hydraulic passage connected to said first hydraulic passage intermediate said first and second valve means and to said hydraulically displaceable member, and means in said body member forming a third passage including overload valve means between the high pressure side of said pump device and said reservoir for by-passing said first passage means so that said pump device is inefiective when the pressure at said high pressure side of said pump device exceeds a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS 2,391,703 Hughes Dec. 25, 1945 2,563,912 Belinkin Aug. 14, 1951 2,672,014 Yarger Mar. 16, 1954 2,970,831 Wordsworth Feb. 7, 1961 2,977,110 Kilgore Mar. 28, 1961 FOREIGN PATENTS 767,006 Great Britain J an. 30, 1957 P 1962 R. -r. MARETTE ETAL 3,054,261

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